Optical connector for simultaneously connecting a plurality of fiber optical cables and adapter for said connector

ABSTRACT

An optical connection ( 10 ) simultaneously connects a plurality of fiber optical cables ( 17, 18 ). The optical connection ( 10 ) has at least one plug ( 10 A) in which a number of ferrules corresponding to the number of fiber optical cables ( 17 ) to be connected are mounted with spring-back effect in the direction of connection. Each of the fiber optical cables ( 17 ) to be connected ends in a corresponding ferrule and is fixed thereto. Each ferrule is mounted with spring-back effect in a separate adapter ( 20 ) and the adapters ( 20 ) are disposed and fixed next to one another inside a common housing ( 19 ′) of the at least one plug ( 10 A).

TECHNICAL FIELD

The present invention relates to the field of fiber optics. It concernsan optical plug-in connector for simultaneously connecting a pluralityof fiber-optic cables according to the precharacterizing clause of claim1 and also an insert for such a plug-in connector.

Such a plug-in connector is known for example from the printedpublications U.S. Pat. No. 5,436,993 or U.S. Pat. No. 5,590,229.

PRIOR ART

On account of their high transmission capacity and their immanentinterference immunity, fiber-optic networks are being used increasinglyin various technical areas, such as for example the communicationsinfrastructure of buildings and the like. The reliable andeasy-to-handle, releasable connection between different fiber-opticcables by means of optical plug-in connectors is of decisivesignificance in this respect. Since the complexity of the communicationtasks is constantly growing, it is required for an ever-increasingnumber of cables to be connected to one another and, correspondingly,for an ever-increasing number of such plug-in connections to beaccommodated in a confined space. This is the case in particular when,for reasons of capacity, a plurality of parallel cables are used insteadof one cable and correspondingly have to be simultaneously connected.

A very simple method of changing over from a single (simplex) plug-inconnection to a double (duplex) plug-in connection is to combine twoconventional simplex plug-in connectors with suitable connecting meansto form a duplex plug-in connector. Examples of such a solution aredisclosed in U.S. Pat. No. 5,528,712 or U.S. Pat. No. 5,343,547.Although such a duplex plug-in connector has the advantage that it canbe constructed in a very simple way from already existing simplexplug-in connectors, it is disadvantageous that, with plug-in connectorsof this type, no space is saved, instead it just being ensured that twootherwise unchanged simplex plug-in connectors are actuatedsimultaneously.

On the other hand, there have already been a number of proposals forvery compact, space-saving optical multiple plug-in connectors in whichthe fibers of a plurality of fiber-optic cables or multifiber cables endin a single ferrule of a plug-in connector and are correspondinglyconnected simultaneously when the plug-in connector is actuated. In U.S.Pat. No. 5,727,101, the one cylindrical ferrule of the plug-in connectorcontains two central bores for receiving two optical fibers. In U.S.Pat. No. 5,799,122 there is provided a flat ferrule of rectangular crosssection, in which a plurality of bores for receiving fiber ends arearranged next to one another in a row. In U.S. Pat. No. 5,896,479, useis likewise made of a flat, substantially rectangular ferrule, which isdivided into two separable halves, on each of which parallel, V-shapedgrooves are provided for receiving the fiber ends. With multiple plug-inconnectors of this type, a multiplicity of individual optical fibers canbe connected in a confined space. However, disadvantages are thecomparatively complex fitting of the fiber ends in the ferrules and alack of flexibility in use, because the ferrules are in each case madeindividually for a specific number of fibers. In addition, it isdisadvantageous in the case of the solutions with the V-shaped groovesthat the fibers cannot be centered very easily in comparison with theprior-art solutions described below (known as the ferrule-sleeve-ferrulesystems).

A further solution for multiple plug-in connectors is described in theprinted publications cited at the beginning U.S. Pat. No. 5,590,229 andU.S. Pat. No. 5,436,993. In the case of this solution, based on aferrule-sleeve-ferrule system, each individual fiber of the plug-inconnector is inserted into a ferrule of its own. The variousferrules—individually sprung—are mounted and held in a common carrierbody (88, 90 in FIG. 4 of U.S. Pat. No. 5,590,229 and 31 in U.S. Pat.No. 5,436,993). Although in the case of this solution the fitting of theoptical fiber ends in the ferrules is much easier than in theaforementioned ferrules with multiple bores, here, too, the flexibilitywhich is advantageous in many cases is lacking, because the carrierbodies are in each case made individually for a specific number offerrules or fibers.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a compact opticalplug-in connector for simultaneously connecting a plurality offiber-optic cables which avoids the disadvantages of the known solutionsand is distinguished in particular by easy fitting of the optical fibersand great flexibility in use.

The object is achieved by the features of claims 1 and 13 in theirentirety. The essence of the invention is to provide individual sprungferrules for each of the fibers, to preassemble these sprung ferrules inseparate inserts and, for forming a multiple plug-in connector, toaccommodate a plurality of these inserts next to one another in a commonhousing. By the use of individual ferrules, the fitting of the fiberends is made easier and at the same time a high centering accuracy ofthe fibers is achieved. The preassembly of the ferrules in separateinserts achieves improved flexibility, because different numbers ofinserts can be combined in a simple way to form a plug-in connector. Onaccount of the preassembled inserts, it is possible to dispense withintermediate or parting walls between the inserts in the housing.

A first preferred refinement of the invention is characterized in thatthe inserts are releasably fastened in the common housing, and that theinserts are fastened in the common housing with snap-in engagement. As aresult, simplified mounting and removal of the inserts is made possible,accompanied at the same time by a stable construction of the plug-inconnection.

A second preferred refinement of the plug-in connector according to theinvention is distinguished by the fact that the inserts respectivelyhave a securing means, preferably consisting of a plastic, in the formof a rectangular frame, which is elongate in the plugging direction,encloses an inner space and in the front side of which an opening isprovided for the ferrule and in the rear side of which a through-bore isprovided for leading the fiber-optic cable through, that, for thespring-mounting of the ferrule, a spring element, in particular in theform of a helical spring, is mounted in the inner space of the securingmeans, that the ferrule is inserted into an inner part, which isarranged in the inner space of the securing means and preferablyconsists of a metal, that the inner part has a guide sleeve for guidingthe spring element, and that means which permit an adjustment of theinner part by rotation about its longitudinal axis into differentangular positions are provided on the inner part. It is preferred forthe adjusting means to comprise an adjusting portion of square crosssection, which adjoins the guide sleeve in the front region of the innerpart and has a receiving bore for receiving the ferrule, and on whichthe spring element is supported with its front end. As a result, astable and adjustable sprung mounting of the ferrule in the insert isachieved with few components.

According to a further refinement, the releasable and snap-engagingsecurement of the inserts in the housing can be realized particularlysimply if, in the case of the securing means, a side wall in each casehas a resilient portion with an engagement step arranged on it, and ifsnap-in openings into which the securing means engage with theirengagement steps when the inserts are pushed into the housing areprovided in the common housing.

A preferred refinement of the inserts according to the invention ischaracterized in that the ferrule is inserted into an inner part, whichis arranged in the inner space of the securing means and preferablyconsists of a metal, that the inner part has a guide sleeve for guidingthe spring element, that means which permit an adjustment of the innerpart by rotation about its longitudinal axis into different angularpositions are provided on the inner part, and that the adjusting meanscomprise an adjusting portion of square cross section, which adjoins theguide sleeve in the front region of the inner part and has a receivingbore for receiving the ferrule, and on which the spring element issupported with its front end.

Further embodiments emerge from the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

The invention is to be explained in more detail below on the basis ofexemplary embodiments in conjunction with the drawing, in which

FIG. 1 shows in a perspective side view a preferred exemplary embodimentof a plug-in connector according to the invention in the form of what isknown as a “backplane connector”, in which (four) fiber-optic cables ofa circuit board are connected by means of a plug and a socket tocorresponding cables of a mounting backplane;

FIG. 2 shows in cross section the plug according to FIG. 1 inserted intothe socket, with its four inserts and ferrules arranged in series nextto one another;

FIG. 3 shows in a perspective exploded representation, seen obliquelyfrom the front, the construction of an insert, as used in the example ofFIG. 1; and

FIG. 4 shows the insert according to FIG. 3, seen obliquely from therear.

WAYS OF IMPLEMENTING THE INVENTION

In FIG. 1, a preferred exemplary embodiment of a plug-in connectoraccording to the invention in the form of what is known as a “backplaneconnector” is reproduced in a perspective side view. In the presentexample, the optical plug-in connector 10, represented in the plugged-instate, releasably connects four fiber-optic cables 17 arranged next toone another of a circuit board (“board”) 14 to four correspondingoptical cables 18, which lead away outward from a mounting backplane(“backplane”) 11. The circuit board 14 is in this case oriented at rightangles to the mounting backplane 11. The optical plug-in connector 10comprises a plug 10A, fixedly mounted on the edge of the circuit board11, and, matching the plug, [lacuna] socket 10B, with an inner housing13, which is mounted displaceably in the plugging direction in an outerhousing 12. The outer housing 12 is in this case fastened (for examplescrewed) by means of a flange 12A in an opening in the mountingbackplane 11. The plug 10A has a body 15, which merges at one end with aplug-in part 19. With this plug-in part 19, it plugs into acorresponding plug-in opening of the socket 10B. The plug 10A and theends of the fiber-optic cables 17 located therein can be protectedagainst soiling or damage and secured to prevent unintentional escape ofradiation by a protective flap 16, which is swivel-mounted on the body15 and is swiveled back to the rear before plugging-in.

According to the invention, each of the four fiber-optic cables 17within the plug 10A or the plug-in part 19 is assigned an independentinsert 20, which contains the associated sprung ferrule for thefastening of the free fiber end and is held together with the otheridentical inserts in snap-in engagement in a common housing 19′ of theplug-in part 19. For the purpose of the snap-in engagement, four snap-inopenings 21 are provided next to one another on the upper side of thehousing in the example of FIG. 1. The position of the inserts 20 withtheir ferrules 23 in the housing 19′ can be seen from FIG. 2.

According to FIGS. 3 and 4, an individual preassemblable insert 20comprises the ferrule 23 (material: for example zirconia; diameter: forexample 1.25 mm), an inner part 24 (of metal), a spring element 28 inthe form of a helical spring, a frame-shaped securing means 29(injection-molded part of plastic), a crimping neck 37 (of metal) and acrimping sleeve 41 (likewise of metal). It goes without saying that,instead of the helical spring, some other spring element, for example arubber tube, may also be used. The securing means 29 forms the basiccomponent of the insert 20 and gives the insert 20 the necessarymechanical stability. The remaining components 23, 24, 28, 37 and 41 areaccommodated in the securing means 29 or attached to the securing means29. The securing means 29 has the form of a rectangular frame, which iselongate in the plugging direction and encloses an inner space 33. Inthe front wall (front side) of the frame, an opening 30 for the ferrule23 is provided. Provided in the rear wall (rear side) is a through-bore34 for leading the fiber-optic cable 17 through, and a rectangularreceiving space 35. Arranged on the outer side of the rear wall is asquare clearance 42 (FIG. 4).

The crimping neck 37 comprises a square holding plate 39, which isadjoined at the front and rear in the axial direction in each case by apipe connecting piece 38 and 40, respectively. The front pipe connectingpiece 38 additionally bears a concentric annular bead 43. When thecrimping neck 37 is pressed into the through-bore 34 of the securingmeans 29, the pipe piece 38 engages with its annular bead 43 in thereceiving space 35. At the same time, the holding plate 39 comes to liein the clearance 42 and in this way secures the crimping neck 37,pressed into the securing means 29, against being twisted by a torsionalforce acting on the cable 17. The front pipe connecting piece 38,protruding into the inner space 33 when the crimping neck 37 is in itspressed-in state, serves for supporting the helical spring 28 insertedinto the inner space 33. The rear pipe connecting piece 40, protrudingrearward out of the securing means 29, serves for securing the tensionrelief of the fiber-optic cable 17 by means of the crimping sleeve 41pushed over it and subsequently pressed.

The ferrule 23, the inner part 24 and the helical spring 28 are mountedin the inner space 33 of the securing means 29. The inner part 24comprises a guide sleeve 29 for guiding the helical spring 28 and alsoan adjusting portion 26 of square cross section. The adjusting portion26 adjoins in the front region of the inner part 24 the guide sleeve 27and has a receiving bore 25 for receiving the ferrule 23. The helicalspring 28, pulled over the guide sleeve 27, is supported with its frontend on the rear side of the adjusting portion 26. The ferrule 23 ispressed into the receiving bore 25 on the inner part 24 and insertedtogether with the inner part 24 and the pushed-on helical spring 28 fromthe open side of the securing means into the inner space 33. In orderthat the ferrule 23 can assume its place in the front opening 30unhindered, this opening 30 is formed such that it is open to the side.The interplay between the square adjusting portion 26 and therectangular inner space 33 permits an adjustment of the inner part 24(or of the fiber) by rotation about its longitudinal axis into differentangular positions (in 4 steps of 90° in each case). The helical spring28 thereby presses the inner part against the front side of the securingmeans 29, so that the adjusted position can be retained. To give thehelical spring 28 additional lateral retention in the inner space 33,elongate delimiting elements 36 may be formed onto the inner side of thelongitudinal walls of the securing means.

However, instead of the rectangular or square configuration with itsadjustability in 90° steps, it is also conceivable to provide, forexample, a hexagonal configuration with an adjustability in 60° steps.The inserts could then correspondingly have a hexagonal cross-sectionalprofile and then be arranged next to one another and one above the otherin a kind of honeycomb structure, in order in this way for example tooptimally fill a circular housing of a plug-in connector.

In order that the inserts 20 can be inserted into the common housing 19′with snap-in engagement, in the case of each securing means 29 theupper-lying side wall in each case has a resilient portion 31 protrudingoutward in a slightly V-shaped manner, with an engagement step 32arranged on it, which releasably engages in the associated snap-inopening 21 on the housing 19′ when the insert 20 is pushed in. Bypressing down the engagement step 32, the insert 20 can then be pulledout again rearward from the housing 19′.

The minimal dimensions of all the components allow optimum seriesarrangement with the insert 20. The securing means 29 may additionallyhave at the front on the inner side a draft (bevel) (not shown in FIG.3), so that, although the inner part 24 has play, it is kept pressed bythe helical spring into the bevel absolutely without play. With thesnap-in device 31, 32, the securing means 29, and consequently theentire insert 20, can be plugged into a housing 19′ of virtually anydesired design, so that multiple connections are possible with only oneplug housing of any desired variation.

The invention has been explained above on the basis of the example of a“backplane connector”, in which there is a plug (“male”) and a socket(“female”). It goes without saying that the concept according to theinvention is also and specifically suitable for plug-in connectorswhich—as represented in U.S. Pat. No. 5,436,993—comprise two identicalplugs and a coupling lying in between (ferrule-sleeve-ferrule system).

List of Designations

10 optical plug-in connector

10A plug

10B socket

11 mounting backplane

12 outer housing (socket)

12A flange

13 inner housing (socket)

14 circuit board

15 body (plug)

16 protective flap (plug)

17, 18 fiber-optic cable

19 plug-in part

19′ housing (plug-in part)

20 insert

21 snap-in opening

22 crimping sleeve

23 ferrule

24 inner part

25 receiving bore

26 adjusting portion (square)

27 guide sleeve

28 spring element or helical spring

29 securing means (frame-shaped)

30 opening

31 resilient portion

32 engagement step

33 inner space

34 through-bore

35 receiving space (rectangular)

36 delimiting element

37 crimping neck

38, 40 pipe-connecting piece

39 holding plate

41 crimping sleeve

42 clearance (square)

43 annular bead

What is claimed is:
 1. An optical plug-in connector (10) forsimultaneously connecting a plurality of fiber-optic cables (17, 18),comprising at least one plug (10A), in which a number of ferrules (23)corresponding to the number of fiber-optic cables (17) to be connectedare mounted such that each of the ferrules spring back in the pluggingdirection, each of the fiber-optic cables (17) to be connected endingwith its optical fiber in the associated ferrule whereby each of theferrules (23) is mounted in a springing-back manner in an insert (20),each insert (20) within the at least one plug (10A) being arranged nextto one another and fixed in a common housing (19′), each insert (20)having a securing means (29) in the form of a rectangular, laterallyopen frame which is elongate in the plugging direction and whichencloses an inner space (33), the frame having an opening (30) in afront side for each of the ferrules (23) and a through-bore (34) in arear side for each fiber-optic cable (17), and a spring element (28) forspring-mounting each of the ferrules (23) in the inner space (33) of thesecuring means (29) of the insert (20).
 2. The optical plug-in connectoras claimed in claim 1, characterized in that the inserts (20) arereleasably fixed in the common housing (19′).
 3. The optical plug-inconnector as claimed in claim 2, characterized in that the inserts (20)are fixed in the common housing (19′) with snap-in engagement.
 4. Theoptical plug-in connector as claimed in claim 1, characterized in thatthe inserts (20) are arranged next to one another in a row in the commonhousing (19′).
 5. The optical plug-in connector as claimed in claim 1,further comprising a socket (10B) into which the plug (10A) is inserted.6. The optical plug-in connector as claimed in claim 1 characterized inthat, in the frame of the securing means (29), a side wall in the framehas a resilient portion (31) with an engagement step (32) arranged onit, and snap-in openings (21) are provided in the common housing (19′)into which the securing means (29) engage with their engagement steps(32) when the inserts (20) are pushed into the common housing (19′). 7.The optical plug-in connector as claimed in claim 1, characterized inthat, for fastening the fiber-optic cable (17) on the securing means(29), there is provided a crimping neck (37), preferably consisting of ametal, which can be pressed with snap-in engagement into thethrough-bore (34) of the securing means (29) and has a pipe connectingpiece (40), protruding rearward from the securing means (29), forfastening a crimping sleeve (41).
 8. The optical plug-in connector asclaimed in claim 1, characterized in that, to simplify the mounting, theopening (30) in the front side of the securing means (29) for receivingeach of the ferrules (23) is open to the side such that each of theferrules (23) can be inserted into the opening (30) from the open side.9. The optical plug-in connector as claimed in claim 1, characterized inthat each of the ferrules (23) is inserted into an inner part (24) whichis arranged in the inner space (33) of the securing means (29) andpreferably consists of a metal, in that the inner part (24) has a guidesleeve (27) for guiding the spring element (28) and in that an adjustingmeans (26) permits an adjustment of the inner part (24) by rotationabout its longitudinal axis into different angular positions areprovided.
 10. The optical plug-in connector as claimed in claim 9,characterized in that the adjusting means comprises an adjusting portion(26) of square cross section, which adjoins the guide sleeve (27) in-thefront region of the inner part (24) and has a receiving bore (25) forreceiving each of the ferrules (23) and on which the spring element (28)is supported with its front end.
 11. An insert for an optical plug-inconnector (10) for simultaneously connecting a plurality of fiber-opticcables (17, 18), comprising at least one plug (10A), in which a numberof ferrules (23) corresponding to the number of fiber-optic cables (17)to be connected are mounted such that each of the ferrules spring backin the plugging direction, each of the fiber-optic cables (17) to beconnected ending with its optical fiber in an the associated ferrule andbeing fastened there, whereby each of the ferrules (23) is mounted in aspringing-back manner in an insert (20), each insert (20) within the atleast one plug (10A) being arranged next to one another and fixed in acommon housing (19′), each insert (20) having a securing means (29) inthe form of a rectangular, laterally open frame, which is elongate inthe plugging direction and which frame encloses an inner space (33), andthe frame having an opening (30) in a front side for each of theferrules (23) a through-bore (34) in a rear side for the fiber-opticcable (17), and a spring element (28) for spring-mounting of each of theferrules (23) in the inner space (33) of the securing means (29) of theinsert (20).
 12. The insert as claimed in claim 11, characterized thateach of the ferrules (23) is inserted into an inner part (24), which isarranged in the inner space (33) of the securing means (29) and consistsof a metal, in that the inner part (24) has a guide sleeve (27) forguiding the spring element (28), and in that adjusting means (26)permits an adjustment of the inner part (24) by rotation about itslongitudinal axis into different angular position are provided.
 13. Theinsert as claims in claim 12 characterized in that the adjusting meanscomprise an adjusting portion (26) of square cross section, whichadjoins the guide sleeve (27) in the front region of the inner part (24)and has a receiving bore (25) for receiving each of the ferrules (23)and on which the spring element (28) is supported with its front end.14. The insert as claimed in claim 11, characterized in that, forfastening the fiber-optic cable (17) on the securing means (29), thereis provided a crimping neck (37), consisting of metal, which can bepressed with snap-in engagement into the through-bore (34) of thesecuring means (29), and has a pipe connecting piece (40), protrudingrearward from the securing means (29), for fastening a crimping sleeve(41).